#include <string>
#include <iostream>
#include <cmath>
#include <ctime>
#include <iomanip>
#include <fstream>
#include <stack>
#include <algorithm>
using namespace std;
int main()
{
    string *c = new string[100];
    int i = 0, h, o;
    string g, n = "";
    while (cin >> g)
    {
        c[i++] = g;
    }
    for(int j=0;j<i;j++)
    {
        if(c[j]=="zero")
            n+="0";
        else if (c[j]=="one")
            n+="1";
        else if (c[j]=="two")
            n+="2";
        else if (c[j]=="three")
            n+="3";
        else if (c[j]=="four")
            n+="4";
        else if (c[j]=="five")
            n+="5";
        else if (c[j]=="six")
            n+="6";
        else if (c[j]=="seven")
            n+="7";
        else if (c[j]=="eight")
            n+="8";
        else if (c[j]=="nine")
            n+="9";
        else
        {
            cout<<"Wrong input";
            return 0;

        }
    }
    if(n.size() < 3 || n.size() > 3)
    {
        cout<<"Wrong input";
        return 0;
    }
    h = stoi(n);
    int* a = new int[1000];
    for (int i = 0; i < 1000; i++)
        a[i] = i;
    for (int p = 2; p < 1000; p++)
    {
        if (a[p] != 0)
        {
            if(abs(a[p] - stoi(n)) < h)
            {
                    h = abs(a[p] - stoi(n));
                    o = p;
            }
        for (int j = p * p; j < 1000; j += p)
            a[j] = 0;
        }
    }
    cout << a[o];
}
